Hyponatremia in Cirrhosis--Pathogenesis, Treatment, and Prognostic Significance

Hyponatremia in the Context of Liver Disease

Hyponatremia is common in patients with liver disease and is associated with increased mortality, morbidity, and a reduced quality of life. In liver transplantation, the inclusion of hyponatremia in organ allocation scores has reduced waitlist mortality. Portal hypertension and the resulting lowering of the effective arterial blood volume are important pathogenetic factors, but in most patients with liver disease, hyponatremia is multifactorial. Treatment requires a multifaceted approach that tries to reduce electrolyte-free water intake, restore urinary dilution, and increase nonelectrolyte solute excretion. Albumin therapy for hyponatremia is a peculiarity of advanced liver disease. Its use appears to be increasing, while the vaptans are currently only given in selected cases. Osmotic demyelination is a special concern in patients with liver disease. Serial checks of serum sodium concentrations and urine volume monitoring are mandatory.

The V2 receptor antagonist tolvaptan counteracts proliferation and invasivity in human cancer cells

PURPOSE

Hyponatremia, the most frequent electrolyte alteration in clinical practice, has been associated with a worse prognosis in cancer patients. On the other hand, a better outcome has been related to serum sodium normalization. In vitro studies have shown that low extracellular sodium promotes cancer cells proliferation and invasiveness. Tolvaptan, a selective vasopressin receptor type 2 (V₂) antagonist, has been effectively used in the last decade for the treatment of hyponatremia secondary to the Syndrome of Inappropriate Antidiuresis. A few in vitro data suggested a direct role of tolvaptan in counteracting cancer progression, so far. The aim of this study was to evaluate the effect and the mechanism of action of tolvaptan in cell lines from different tumours [i.e. colon cancer (HCT-8), hepatocarcinoma (HepG2), neuroblastoma (SK-N-AS)].

METHODS AND RESULTS

First, we showed that these cell lines express the V₂ receptor. Tolvaptan significantly reduced cell proliferation with an IC₅₀ in the micromolar range. Accordingly, reduced levels of cAMP, of the catalytic α subunit of PKA, and a reduced pAKT/AKT ratio were observed. Tolvaptan effectively inhibited cell cycle progression, whereas it induced apoptotis. Furthermore, it reduced cell invasiveness. In particular, anchorage-independent growth and the activity of collagenases type IV were blunted in the three cell lines. Accordingly, tolvaptan counteracted the RhoA/ROCK1-2 pathway, which has a pivotal role in regulating cell movement.

CONCLUSIONS

Overall, these findings indicate that tolvaptan effectively inhibits tumour progression in vitro. Further studies should clarify whether the V₂ receptor might be considered a possible target in anti-cancer strategies in the future.

Acid-base abnormalities and liver dysfunction

In addition to the kidneys and lungs, the liver also plays an important role in the regulation of the Acid-Base Equilibrium (ABE). The involvement of the liver in the regulation of ABE is crucial because of its role in lactic acid metabolism, urea production and in protein homeostasis. The main acid-base imbalance that occurs in patients with liver cirrhosis is Respiratory Alkalosis (RAlk). Due to the fact that in these patients additional pathophysiological mechanisms that affect the ABE are present, other disorders may appear which compensate or enhance the primary disorder. Conventional ABE reading models fail to identify and assess the underlying disorders in patients with liver cirrhosis. This weakness of the classical models led to the creation of new physicochemical mathematical models that take into account all the known parameters that develop and affect the ABE. In addition to the RAlk, in patients with liver cirrhosis, metabolic alkalosis (due to hypoalbuminemia), hyponatremic metabolic acidosis, hyperchloremic metabolic acidosis, lactic acidosis and metabolic alkalosis due to urea metabolism are some of the pathophysiological mechanisms that affect the ABE.

Clinical Implications, Evaluation, and Management of Hyponatremia in Cirrhosis

Hyponatremia is the most common electrolyte abnormality in patients with decompensated cirrhosis on Liver Transplantation (LT) waiting list. Most of these patients have dilutional or hypervolemic hyponatremia secondary to splanchnic vasodilatation. Excessive secretion of the antidiuretic hormone also plays an important role. Hypervolemic hyponatremia is commonly associated with refractory ascites, spontaneous bacterial peritonitis, and hepatic encephalopathy. Although uncommon, the use of diuretics and laxatives can cause hypovolemic hyponatremia that is characterized by the striking absence of ascites or pedal edema. Clinical features are often nonspecific and depend on the acuity of onset rather than the absolute value of serum sodium. Symptoms may be subtle, including nausea, lethargy, weakness, or anorexia. However, rarely patients may present with confusion, seizures, psychosis, or coma. Treatment includes discontinuation of diuretics, beta-blockers, and albumin infusion. Hypertonic saline (3%) infusion may be used in patients with very low serum sodium (<110 mmol/L) or when patients present with seizures or coma. Short-term use of Vasopressin (V₂) receptor antagonists may also be used to normalize sodium levels prior to LT. However, all these measures may be futile, and LT remains the definite treatment in these patients to improve survival. In this review, we describe the classification, pathogenesis of hyponatremia, and its clinical implications in patients with cirrhosis. Approach to these patients along with management will also be discussed briefly.

Serum potassium levels and prognosis in HBV-associated decompensated cirrhosis

Background

Serum potassium disorders are commonly seen in patients with advanced cirrhosis and have a detrimental effect on clinical outcome, but its role in HBV‐related decompensated cirrhosis (DeCi) is remained to be illustrated. We aim to assess the effects of serum potassium on outcomes in HBV‐DeCi patients.

Methods

Retrospective study included 155 subjects. Multivariate analysis was used to determine the independent prognostic factor. Predictive ability of mortality for variables was determined using the receiver operating characteristics curves.

Results

The 30‐day in‐hospital mortality was 12.9%. Serum potassium levels differed markedly between survivors and non‐survivors. On multivariate analysis, Model for End‐Stage Liver Disease (MELD) score and serum potassium level were identified as independent predictors of outcomes in HBV‐DeCi patients. The combination of serum potassium and MELD score could improve prognostic accuracy in these patients.

Conclusions

Our findings suggest that serum potassium is an effective predictor for poor outcomes in HBV‐DeCi patients.

Hyponatremia in Cirrhosis: An Update

Hyponatremia is frequently seen in patients with ascites secondary to advanced cirrhosis and portal hypertension. Although not apparent in the early stages of cirrhosis, the progression of cirrhosis and portal hypertension leads to splanchnic vasodilation, and this leads to the activation of compensatory mechanisms such as renin-angiotensin-aldosterone system (RAAS), sympathetic nervous system, and antidiuretic hormone (ADH) to ameliorate low circulatory volume. The net effect is the avid retention of sodium and water to compensate for the low effective circulatory volume, resulting in the development of ascites. These compensatory mechanisms lead to impairment of the kidneys to eliminate solute-free water in decompensated cirrhosis. Nonosmotic secretion of antidiuretic hormone (ADH), also known as arginine vasopressin, further worsens excess water retention and thereby hyponatremia. The management of hyponatremia in this setting is a challenge as conventional therapies for hyponatremia including fluid restriction and correction of hypokalemia are frequently inefficacious. In this review, we discuss the pathophysiology, complications, and various treatment modalities, including albumin infusion, selective vasopressin receptor antagonists, or hypertonic saline for patients with severe hyponatremia and those awaiting liver transplantation.

Metabolic acidosis in critically ill patients with cirrhosis: Epidemiology and short-term mortality risk factors

BACKGROUND/AIMS

Metabolic acidosis is a common complication in patients with cirrhosis at the intensive care units (ICUs) and associated with increased mortality. The aim of our research was to explore the epidemiology and risk factors of metabolic acidosis in critically ill patients with cirrhosis.

MATERIALS AND METHODS

A total of 975 patients with cirrhosis were selected into our study, and all participants were followed up for at least 28 days. Cox regression model and machine-learning algorithm were used to identify the importance of different risk factors, respectively. Finally, an improved prognostic model as Model for End-stage Liver Disease and metabolic acidosis (MELD-MA) was developed.

RESULTS

Among the 975 patients with liver cirrhosis, 506 had metabolic acidosis, including 257 patients who had decompensated metabolic acidosis at ICU admission. The 28-day mortality was 41% (206/506) in patients with metabolic acidosis. Bilirubin (hazard ratio (HR): 1.023, 95% confidence interval (CI): 1.011-1.036), international normalized ratio (HR: 1.527, 95% CI: 1.332-1.750), pH (HR: 0.173, 95% CI: 0.047-0.640), BE-Lac (HR: 0.907, 95% CI: 0.868-0.948), and BE-Na (HR: 0.923, 95% CI: 0.859-0.991) were considered as independent prognostic parameters for 28-day mortality. MELD-NA had significantly higher discrimination (area under the receiver operating characteristic curve 0.79) than MELD and Child-Pugh score.

CONCLUSION

Critically ill patients with cirrhosis have a high mortality rate and poor prognosis because of the high prevalence of metabolic acidosis. Lactic acidosis is the worst prognosis of all types of metabolic acidosis. MELD-MA performs well on the short-term mortality assessment in critically ill patients with cirrhosis and metabolic acidosis.

Impact of Vaptans on Clinical Outcomes in Cirrhosis Patients: A Meta-Analysis of Randomized Controlled Trials

Background: Vaptans have been confirmed to mobilize ascites and improve hyponatremia in cirrhosis patients. However, the effects of vaptans on all-cause mortality, ascites-related complications, and adverse events in cirrhosis patients have not been fully determined.

Objectives: To systematically evaluate the impact of vaptans on the clinical outcomes in patients with cirrhosis.

Materials and Methods: A systematic review and meta-analysis was performed. The PubMed, Embase, and Cochrane’s Library electronic databases were systematically searched for randomized controlled trials (RCTs) investigating the clinical efficacy of vaptans in cirrhosis patients. The results were pooled with a random-effect model.

Results: Eighteen RCTs containing 3,059 cirrhosis patients with ascites and/or hyponatremia were included. Meta-analysis showed that vaptans did not significantly affect the risk of all-cause mortality (RR: 1.02, 95% CI: 0.87 to 1.08, p = 0.83; I² = 2%), consistent with studies with short-term (< 26 weeks) and long-term (≥ 26 weeks) follow-up durations. Additionally, vaptans did not affect the incidence of variceal bleeding (RR: 0.96, p = 0.86), showed a trend of reduced incidence of hepatic encephalopathy (RR: 0.86, p = 0.09), significantly reduced the incidence of spontaneous bacterial peritonitis (RR: 0.75, p = 0.03), but did not significantly affect the risk of hepatorenal syndrome or renal failure (RR: 1.09, p = 0.36). Vaptans did not affect the incidence of adverse events in cirrhosis patients.

Discussion: Treatment with vaptans is not associated with improved survival in cirrhosis patients, although it may reduce the risk of hepatic encephalopathy and spontaneous bacterial peritonitis in these patients. The limitations of the current study include limited number of available studies, small sample sizes of the included studies, variations of baseline patient characteristics, and differences in the dose and duration of vaptans.

Serum sodium as a risk factor for hepatic encephalopathy in patients with cirrhosis and ascites

BACKGROUND AND AIM

Hyponatremia is associated with development of hepatic encephalopathy (HE), but the nature of the relationship between serum sodium and HE incidence is unknown. We examined the association between serum sodium, changes in serum sodium, and HE incidence using data from three randomized trials of satavaptan in cirrhosis patients with ascites.

METHODS

During follow-up, patients were examined for HE, and serum sodium was measured regularly. We used fractional polynomials to estimate the nature of the association between current serum sodium and hazard rate of HE (e.g. with a linear, logarithmic, or exponential slope) and Cox regression to adjust for confounders. Moreover, we examined the association between serum sodium at inclusion and 30-day and 1-year cumulative risk of HE. Finally, we examined the effect of "change in serum sodium since inclusion" on the hazard rate of HE.

RESULTS

We included 1116 patients of whom 302 developed HE. Median serum sodium at inclusion was 137 (interquartile range, 134-139). The lower the current serum sodium, the higher the rate of HE. Specifically, the confounder-adjusted HE hazard rate increased linearly by 8% (adjusted hazard ratio = 1.08, 95% confidence interval: 1.06-1.10) for every mmol/L decrease in serum sodium over the range of measured values. Current serum sodium had a stronger effect on the HE rate than the changes in serum sodium since inclusion.

CONCLUSION

The hazard rate of HE development increased by 8% for every mmol/L decrease in serum sodium. Further, current serum sodium had a stronger effect on the HE rate than changes in serum sodium.

Acid-base disorders in liver disease

Alongside the kidneys and lungs, the liver has been recognised as an important regulator of acid-base homeostasis. While respiratory alkalosis is the most common acid-base disorder in chronic liver disease, various complex metabolic acid-base disorders may occur with liver dysfunction. While the standard variables of acid-base equilibrium, such as pH and overall base excess, often fail to unmask the underlying cause of acid-base disorders, the physical-chemical acid-base model provides a more in-depth pathophysiological assessment for clinical judgement of acid-base disorders, in patients with liver diseases. Patients with stable chronic liver disease have several offsetting acidifying and alkalinising metabolic acid-base disorders. Hypoalbuminaemic alkalosis is counteracted by hyperchloraemic and dilutional acidosis, resulting in a normal overall base excess. When patients with liver cirrhosis become critically ill (e.g., because of sepsis or bleeding), this fragile equilibrium often tilts towards metabolic acidosis, which is attributed to lactic acidosis and acidosis due to a rise in unmeasured anions. Interestingly, even though patients with acute liver failure show significantly elevated lactate levels, often, no overt acid-base disorder can be found because of the offsetting hypoalbuminaemic alkalosis. In conclusion, patients with liver diseases may have multiple co-existing metabolic acid-base abnormalities. Thus, knowledge of the pathophysiological and diagnostic concepts of acid-base disturbances in patients with liver disease is critical for therapeutic decision making.

Prevention of the Osmotic Demyelination Syndrome After Liver Transplantation: A Multidisciplinary Perspective

The osmotic demyelination syndrome (ODS) is a serious neurologic condition that occurs in the setting of rapid correction of hyponatremia. It presents with protean manifestations, from encephalopathy to the "locked-in" syndrome. ODS can complicate liver transplantation (LT), and its incidence may increase with the inclusion of serum sodium as a factor in the Mayo End-Stage Liver Disease score. A comprehensive understanding of risk factors for the development of ODS in the setting of LT, along with recommendations to mitigate the risk of ODS, are necessary. The literature to date on ODS in the setting of LT was reviewed. Major risk factors for the development of ODS include severe pretransplant hyponatremia (serum sodium [SNa] < 125 mEq/L), the magnitude of change in SNa pre- versus posttransplant, higher positive intraoperative fluid balance, and the presence of postoperative hemorrhagic complications. Strategies to reduce the risk of ODS include correcting hyponatremia pretransplant via fluid restriction and/or ensuring an appropriate rate of increase from the preoperative SNa via close attention to fluid and electrolyte management both during and after surgery. Multidisciplinary management involving transplant hepatology, nephrology, neurology, surgery, and anesthesiology/critical care is key to performing LT safely in patients with hyponatremia.

Portopulmonary hypertension and hepatorenal syndrome. Two faces of the same coin

Portopulmonary hypertension and hepatorenal syndrome are both severe local hypertensive complications of liver cirrhosis and portal hypertension. Both are characterized by vasoconstrictive manifestations regarding pulmonary and renal vascular network, respectively. This review addresses the mechanisms underlying the development of vasoconstriction that leads to local vascular hypertension in the lung and in the kidney with the result of organ dysfunction. Potential therapeutic options are available for the management of these two syndromes as a bridge for liver transplantation; clinical efficacy depends in part on the time and rapidity of intervention and in part on how serious the chain of events is that has triggered the entire vasoconstrictive process.

Electrolyte and Acid-Base Disturbances in End-Stage Liver Disease: A Physiopathological Approach

Electrolyte and acid-base disturbances are frequent in patients with end-stage liver disease; the underlying physiopathological mechanisms are often complex and represent a diagnostic and therapeutic challenge to the physician. Usually, these disorders do not develop in compensated cirrhotic patients, but with the onset of the classic complications of cirrhosis such as ascites, renal failure, spontaneous bacterial peritonitis and variceal bleeding, multiple electrolyte, and acid-base disturbances emerge. Hyponatremia parallels ascites formation and is a well-known trigger of hepatic encephalopathy; its management in this particular population poses a risky challenge due to the high susceptibility of cirrhotic patients to osmotic demyelination. Hypokalemia is common in the setting of cirrhosis: multiple potassium wasting mechanisms both inherent to the disease and resulting from its management make these patients particularly susceptible to potassium depletion even in the setting of normokalemia. Acid-base disturbances range from classical respiratory alkalosis to high anion gap metabolic acidosis, almost comprising the full acid-base spectrum. Because most electrolyte and acid-base disturbances are managed in terms of their underlying trigger factors, a systematic physiopathological approach to their diagnosis and treatment is required.

Treatment of Cirrhosis-Associated Hyponatremia with Midodrine and Octreotide

BACKGROUND

Hyponatremia in the setting of cirrhosis is a common electrolyte disorder with few therapeutic options. The free water retention is due to non-osmotic vasopressin secretion resulting from the cirrhosis-associated splanchnic vasodilatation. Therefore, vasoconstrictive therapy may correct this electrolyte abnormality. The aim of this study was to assess the efficacy of midodrine and octreotide as a therapeutic approach to increasing urinary electrolyte-free water clearance (EFWC) in the correction of cirrhosis-associated hyponatremia.

METHODS

This observational study consisted of 10 patients with cirrhosis-associated hyponatremia. Hypovolemia was ruled out as the cause of the hyponatremia with a 48-h albumin challenge (25 g IV q6 h). Patients whose hyponatremia failed to improve with albumin challenge were started on midodrine and octreotide at 10 mg po tid and 100 μg sq tid, respectively, with rapid up-titration as tolerated to respective maximal doses of 15 mg tid and 200 μg tid within the first 24 h. We assessed urinary EFWC and serum sodium concentration before and 72 h after treatment.

RESULTS

Pretreatment serum sodium levels ranged from 119 to 133 mmol/L. The mean pretreatment serum sodium concentration ± SEM was 124 mmol/L ± 1.6 vs 130 mmol/L ± 1.5 posttreatment (p = 0.00001). The mean pretreatment urinary EFWC ± SEM was 0.33 L ± 0.07 vs 0.82 L ± 0.11 posttreatment (p = 0.0003).

CONCLUSION

Our data show a statistically significant increase in serum sodium concentration and urinary EFWC with the use of midodrine and octreotide in the treatment of cirrhosis-associated hyponatremia.

The clinical management of abdominal ascites, spontaneous bacterial peritonitis and hepatorenal syndrome: a review of current guidelines and recommendations

Several pathogenic processes have been implicated in the development of abdominal ascites. Portal hypertension, most usually in the context of liver cirrhosis, can explain about 75% of the cases, whereas infective, inflammatory and infiltrative aetiologies can account for the rest. In this article, we discuss the consensus best practice as published by three professional bodies for the management of ascites, spontaneous bacterial peritonitis (SBP) and hepatorenal syndrome (HRS). The aim of this study was to compare available clinical guidelines and identify areas of agreement and conflict. We carried out a review of the guidance documentation published by three expert bodies including the British Society of Gastroenterology, the European Association for the Study of the Liver (EASL) and the American Association for the Study of Liver Diseases (AASLD), as well as a wider literature search for ascites, SBP and HRS. Abdominal ultrasonography, diagnostic paracentesis and ascitic fluid cultures are recommended by all three guidelines, especially when there is strong clinical suspicion for infection. EASL and AASLD advocate the use of ascitic amylase and mycobacterial cultures/PCR when there is strong suspicion for tuberculosis and pancreatitis, respectively. Ascitic cytology can be useful when cancer is suspected and has a good diagnostic yield if performed correctly. EASL supports the use of urinary electrolytes for all patients; however, the British Society of Gastroenterology and AASLD only recommend their use for therapy monitoring. All three societies recommend cefotaxime as the antibiotic of choice for SBP and large-volume paracentesis for the management of ascites greater than 5 l in volume. For HRS, cautious diuresis, volume expansion with albumin and the use of vasoactive drugs are recommended. There appears to be good concordance between recommendations by the European, American and British guidelines for the management of ascites and the possible complications arising from it.